Grade 11 Functions
posted by Jim on .
A baseball player hits a foul ball into the stands. He wants to know where the ball would've landed if the stands had not been there. The points they give you are: The yintercept (0,1), (2,2.5) and (134,18). I'm pretty sure you are looking for the zeroes.

assuming the ball's trajectory to be a parabola,
y = ax^2 + bx + c
Plug in the three points and solve for y=0, because that;'s how high the ball would have been when it hit the ground.
1 = a*0 + b*0 + c
so, c=1
y = ax^2 + bx + 1
2.5 = 4a + 2b
18 = 17956a + 134b
multiply the first by 67 and subtract from the second, and we have
a = 0.00845
b = 1.2669
s, we have
y = .00845x^2 + 1.2669x + 1
When y=0, x = 150.714
Must have hit into the stands about halfway to the outfield fence.